2007-08 Snow Totals

The 2007-08 snowfall, in inches, is shown in the above map. Nineteen general snowfall events
lasting from just a day or so, to more than a week of semi-continuous
snowfall, were identified during the 2007-08 season.

To make the best use of data, each month of snowfall was analyzed to a grid of values for the region.
Those monthly grids were then summed to form the pattern shown above.
The formation of grids of snow was guided by the use of elevation and the distance to Lake Superior.
In that way even in areas where data is still somewhat sparse the steep ‘gradient’ of snowfall values,
up to about ˝ foot per mile, from shore to inland could be shown.

Data was provided by 64 Soil and Water Conservation District Observers plus 20 National Weather Service
and DNR observers (in St. Louis, Lake, and Cook counties).

2007-08 'events'

Location of 'peak' snow fall

Snowfall deposition varies from the shore of Lake Superior to points inland. The pattern arises
from both changes in the availability of moisture as well as from elevation changes.
Lake Superior, largely ice free for most of most winters, supplies moisture to cold, dry air
flowing across its surface. That moisture can be precipitated out when the air is recooled as
it is lifted when it flows uphill as air crosses the shoreline.

The blue dots, representing individual observers, show the average fraction of the
median of the event's non-zero snowfalls. The green line is a type of weighted running average
of the individual observer values. An overall peak occurs
approximately 8-10 kilometers inland.
That distance is where the land surface has climbed about 75% of the height difference
of the inland highest surfaces and the Lake Superior. On the average the
highest elevation of the land surface occurs at about 25 km inland.
The location of that snowfall approaches the elevation peak but still on the
upslope side is what was expected.

The graph can be stretched logarithmically so that the observers nearest the shore
are more spread out in the graph.